Maximize Your PC’s Security: Troubleshooting Microsoft Defender Antivirus Issues

Encountering issues with Microsoft Defender Antivirus not activating can leave your PC vulnerable to digital threats. Rest assured, this is a common challenge users face, and there are reliable methods to bring the antivirus back to its protective stance. This guide is tailored to help you navigate through the most effective solutions to resolve Microsoft Defender Antivirus activation hiccups.

Step-by-Step Fixes for Microsoft Defender Antivirus Activation Problems

Ensure Real-Time Protection is Enabled

Microsoft Defender Antivirus relies heavily on its real-time protection feature to safeguard your system against malware and other threats. If this feature is off, it may seem as though the antivirus is not operational. Below are the steps to activate real-time protection:

  • Open the Start menu by clicking the Windows icon at the bottom left of your screen or by pressing the Windows + I shortcut key. Then, navigate to Settings.
  • In the Settings window, select Update & Security, move to the Windows Security tab, and proceed to Virus & Threat Protection.
  • Find and click on the Manage settings option under the Virus and threat protection settings section, leading you to where you can toggle on real-time protection.

Temporarily Deactivate Third-party Antivirus Software

The presence of another antivirus program can impede Microsoft Defender Antivirus’s functions. To check if this is the case, you can disable any third-party antivirus software as follows:

  • Access the Task Manager by right-clicking on the taskbar and selecting it or pressing Ctrl+Shift+Esc.
  • Locate the antivirus application, click on it to select, and then choose the ‘Disable’ option to stop it from launching during start-up.
  • Restart your PC and assess if Microsoft Defender Antivirus becomes functional.

Repair Damaged System Files

Corrupt system files can be the culprit behind Microsoft Defender Antivirus not starting. The System File Checker tool can come in handy for such scenarios:

  • Open Command Prompt with admin rights by searching for it and right-clicking to select ‘Run as administrator.’
  • Give affirmation to the User Account Control prompt by clicking “Yes.”
  • Type “sfc /scannow” into the command line and press Enter to initiate the system scan.
  • Upon completion, the tool will automatically restore any damaged files it discovers, potentially correcting the Microsoft Defender Antivirus error.

Utilize DISM Tool to Fix System Image Problems

Deployment Image Servicing and Management (DISM) is another utility found within Windows that can rectify system corruption. Use DISM commands to attempt repairs:

  • Open an elevated Command Prompt window.
  • Enter “DISM.exe /Online /Cleanup-image /Scanhealth” and press Enter.
  • Then, issue the command “DISM.exe /Online /Cleanup-image /Restorehealth” and hit Enter again.
  • Once the process concludes, reboot your computer and verify the status of Microsoft Defender Antivirus.

Restart the Security Center Service

Microsoft Defender Antivirus requires certain services to be running. If these services have halted, restarting them might solve the issue:

  • Trigger the Run dialog by pressing Windows + R keys.
  • Enter “services.msc” and press Enter.
  • Scroll down to the Security Center service, perform a right-click and go into Properties. Confirm it’s set to Automatic startup.
  • If the service is stopped, click “Start” to get it running again.

Activate Microsoft Defender Antivirus via Group Policy

In cases where Group Policy has disabled Microsoft Defender Antivirus, you can reverse this setting:

  • Use the search bar to locate Edit Group Policy and access it.
  • Follow this path: Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus.
  • Double-click the policy named “Turn off Microsoft Defender Antivirus” and change its setting to “Not Configured.” Apply the changes and restart your PC.


Put an end to your worries about your PC’s security by addressing the Microsoft Defender Antivirus activation issue. Remember to keep your system updated and maintain a single antivirus program to avoid software conflicts.

Frequently Asked Questions (FAQs)

Q: What causes Microsoft Defender Antivirus to not turn on?

A: Challenges with Microsoft Defender Antivirus activation may arise due to malware infestations, third-party antivirus interference, damaged system files, or necessary services being turned off. Implement the above solutions to tackle these concerns.

Q: Is it advisable to run Microsoft Defender Antivirus simultaneously with other antivirus software?

A: It is generally not recommended to operate Microsoft Defender Antivirus alongside another antivirus solution, as this could lead to software clashes and performance issues. Ideally, choose one robust antivirus program that meets your security requirements.

Editorial Staff
Editorial Staff
The Bollyinside editorial staff is made up of tech experts with more than 10 years of experience Led by Sumit Chauhan. We started in 2014 and now Bollyinside is a leading tech resource, offering everything from product reviews and tech guides to marketing tips. Think of us as your go-to tech encyclopedia!


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